Expected Turnaround Time
3 - 9 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Documents
For more information, please view the literature below.
Procedures for Hemostasis and Thrombosis: A Clinical Test Compendium
Specimen Requirements
Specimen
Whole blood
Volume
5 mL
Minimum Volume
0.5 mL (Note: This volume does not allow for repeat testing.)
Container
Lavender-top (EDTA) tube (preferred) or yellow-top (ACD) tube
Storage Instructions
Maintain specimen at room temperature or refrigerate. Stable at room temperature and refrigerated for seven days.
Causes for Rejection
Clotted whole blood samples if adequate DNA not obtained; incorrect specimen type; frozen whole blood specimens
Test Details
Use
This test provides information about additional risk for venous thrombosis among individuals known to be heterozygous for factor V Leiden (one copy of mutation). This knowledge aids in prevention of venous thrombosis. Factor V Leiden is the most common genetic risk factor for venous thrombosis and pulmonary embolism. It is present in 5% of the Caucasian population and in 20% to 40% of individuals with a history of venous thromboembolism. Not all individuals who are heterozygous for factor V Leiden will experience a thrombotic event, and the factor V R2 DNA analysis identifies some individuals at risk. Factor V Leiden heterozygotes are at a sevenfold increased risk for venous thrombosis compared to the general population. Coexistence of the R2 polymorphism with factor V Leiden increases that risk by an additional threefold, leading to an increased risk of approximately 16-fold.
Limitations
This is not a diagnostic test. It assesses increased risk of venous thromboembolism due to the presence of the factor V R2 variant in individuals who are heterozygous for factor V Leiden. Not all individuals with factor V R2 and factor V Leiden will have a venous thrombosis event in their lifetimes. Test results should be used in conjunction with clinical observation and other lab results.
Methodology
Polymerase chain reaction (PCR) with restriction enzyme digestion and polyacrylamide gel electrophoresis
References
Alhenc-Gelas M, Nicaud V, Gandrille S, et al. The factor V gene A4070G mutation and the risk of venous thrombosis. Thromb Haemost.1999 Feb; 81(2):193-197.10063990
Castoldi E, Brugge JM, Nicolaes GA, Girelli D, Tans G, Rosing J. Impaired APC cofactor activity of factor V plays a major role in the APC resistance associated with the factor V Leiden (R506Q) and R2 (H1299R) mutations. Blood. 2004 Jun 1; 103(11):4173-4179. 14976057
Faioni EM, Castaman G, Asti D, Lussana F, Rodeghiero F. Association of factor V deficiency with factor V HR2. Haematologica. 2004 Feb; 89(2):195-200. 15003895
Faioni EM, Franchi F, Bucciarelli P, et al. Coinheritance of the HR2 haplotype in the factor V gene confers an increased risk of venous thromboembolism to carriers of factor V R506Q (factor V Leiden). Blood. 1999 Nov 1; 94(9):3062-3066. 10556190
Folsom A, Cushman M, Tsai MY, et al. A prospective study of venous thromboembolism in relation to factor V Leiden and related factors. Blood. 2002 Apr 15; 99(8):2720-2725.
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 503940 | Factor V R2 DNA Analysis | 503942 | FV R2 DNA Analysis Result: | 41103-3 | ||
| 503940 | Factor V R2 DNA Analysis | 503941 | Methodology: | 49549-9 | ||
| 503940 | Factor V R2 DNA Analysis | 503944 | Interpretation: | 35474-6 | ||
| 503940 | Factor V R2 DNA Analysis | 503945 | Comment: | 77202-0 |
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